Cordless angle grinders

Could a cordless angle grinder help save your yacht in the event of a dismasting? Julian Peckham tests four to find out

Apart from being a handy tool to have at the boatyard – for obvious uses like cleaning up corroded metal, grinding off new welds, cutting through rusty fittings and even chopping through glassfibre – a cordless angle grinder could be a vital piece of safety kit for any boat with a mast.

If you’re dismasted at sea in a storm, with the rigging hanging over the side and threatening to capsize the boat, you’ll need to ditch the rig into the depths pretty quickly – and that means cutting through rigging wire and possibly even a buckled mast. Stainless steel rigging wire is notoriously difficult to chop through, even with bolt or wire cutters designed for the job. Wire cutters man enough for the job are inevitably heavy, and require a fair bit of strength to bite through all the strands of wire. And there’s no way a pair of bolt cutters will chop off a mast.

Wouldn’t it be easier to slice the rigging off with an angle grinder? The development of lithium-ion (Li-ion) battery technology now makes this a realistic prospect. Cordless grinders using the oldertechnology nickel cadmium (NiCad) batteries have been around for a good few years, but the problem with NiCad batteries is that over time they’ll self-discharge. If you only make short sailing hops and spend a lot of time with available shore power, this may not be a big difficulty (although another major inconvenience is that, because of ‘memory effect’, you’ll have to fully discharge the battery before recharging), but is no use if you’re spending any length of time at sea.

Li-ion batteries suffer very little self-discharge so they can go unused for weeks or months and still have plenty of power left when you need them – and their charge can be simply topped up, with no ill effects, at your next opportunity.

We tried four widely-available 18V machines to see how they fared. We decided that two batteries were necessary for general use and for safety (if one proves flat in an emergency, then you have another to try), and that there’d obviously need to be a battery charger. All of the angle grinders tested come with a clamping ring spanner, and a side handle that can be screwed in for right- or left-handed use.

How we tested them

Having acquired a length of 6mm 19-strand stainless steel rigging wire, this was clamped to the open jaws of a workmate bench, then the jaws opened slightly further to approximate wire under slight tension. (In reality, of course, there are likely to be some wires which are much more taut if a rig is hanging over the side.) To mimic loose rigging, the wire was simply clamped in the workbench jaws and left dangling free at one end.

Fitting them with a new disc, we then used each grinder to make 20 cuts through taut wire and 20 through loose wire – 40 cuts in all, and more than six times the